Jigsaw puzzles are well known. In a jigsaw puzzle, the objective is to fit together a number of segments in a predetermined manner so as to form a coherent picture or image.
In a prior art document, U.S. Pat. No. 2,493,697, there is shown a puzzle formed of several small jigsaw-type sections. Each jigsaw section can be assembled to form a layer. The different layers are then placed in order onto a base and post to form a three-dimensional figure.
In a further prior art document, U.S. Pat. No. 3,779,558, there is shown a puzzle where pieces can be assembled in a 2-D puzzle or stacked in layers to form a 3-D figure. The order in which the puzzle pieces are assembled in the 2-D puzzle is completely independent of the order in which they are stacked in the three dimensional puzzle. The puzzle shown uses spikes to secure stacked pieces in place. This means that holes are formed in the puzzle pieces and it is therefore not possible to completely reform a perfect planar image. As shown in the patent, the puzzle pieces do not perfectly abut in the stacked puzzle and gaps are left.